I think the general trend is for most sports a reduction or quitting once entering Jr. High and High School. I think the primary reason for it is that most teams focus more on winning, have try-outs, etc, so there is a natural reduction in numbers, fewer teams to play for, less spots to fill on the fewer teams, etc. It would be interesting to see the numbers and verification of the numbers that end up quitting and why, but if I had to speculate why, this would be the primary reason. I also believe that more kids in other sports, where there are less opportunities, end up quitting than in wrestling. I coached High School soccer and saw large numbers of kids quit once they got past the kids level, specifically entering the Jr. High and even more so the High School levels. The lack of emphasis on winning in that sport among small kids (they say they don't even keep score, yea like parents and kids themselves don't keep score), would seem to show that the "lack of pressure" in reality don't prevent the drop out rates. By the way, more kids play soccer in America than any other sport, but those numbers drop off in huge numbers at Jr. High and High School. You don't see that sport complaing about the numbers that quit either, instead they talk about it being the #1 participation sport in America.

There is another issue I think that is important. Kids quitting when they are not good enough to make a team is not really that big of a deal. What I mean by this is that the nature of competition will in and of itself reduce numbers. I used to for example play tennis all of the time. However, after I realized I wasn't any good at the sport I just quit, don't even own a racket any more. The exception to this theory for me is golf. I am not that good, but will not give up my clubs. Fortunately, I measure my success in that game is by how many balls I have lost or found.